Optical lens image stabilization systems

ABSTRACT

The present invention provides optical systems, devices and methods which utilize one or more electroactive polymer actuators to stabilize the image produced by the device or system.

FIELD OF THE INVENTION

The present invention relates to optical lens systems and, inparticular, relates to such systems employing electroactive polymertransducers to adjust the lens to provide auto-focusing, zoom, imagestabilization and/or shutter/aperture capabilities.

BACKGROUND

In conventional optical systems, such as in digital cameras, motors andsolenoids are used as sources of power to displace gears and cams whichact upon optical elements, e.g., lenses, to provide focusing, zoom, andimage stabilization (also referred to as shake prevention). There aremany disadvantages to such conventional systems—power consumption ishigh, response times are long, accuracy is limited and spacerequirements are high.

Advancements in miniaturized technologies have led to high-quality,highly-functioning, light-weight portable devices, and anever-increasing consumer demand for even further improvements. Anexample of this is the development of cellular telephones to include acamera, often referred to as camera phones. While the majority of suchcamera phones employ an all-mechanical lens module having a small formfactor lens, this approach does not offer variable or auto-focusing,zoom and image stabilization capabilities due to the significant numberof moving parts required. For example, zoom capability requires acombination of lens elements, a motor, and a cam mechanism fortransmitting the rotational movement of the motor to linear movement inorder to adjust the relative positions of the lenses and an associatedimage sensor in order to obtain the desired magnification. In additionto the motor and cam mechanism, a plurality of reduction gears are isused to accurately control the relative positioning of the lenses.

Electromagnetic type actuators which include a coil generating amagnetic force where the magnet has a length longer than that of thecoil in the optical axis direction (commonly referred to as “voicecoils”) are commonly employed to perform many of the auto-focus and zoomactuator functions within digital still cameras and, to some extent, incamera phones. This voice coil technology has been widely accepted as itenables small and lighter optical lens systems. However, a downside tolighter and smaller cameras, particularly those with capabilities forlonger exposure times and having higher resolution sensors, is thegreater effect that camera shake, due primarily to hand jitter, has onthe quality of photographs, i.e., causing blurring. To compensate forcamera shake, gyroscopes are often used for image stabilization. Agyroscope measures pitch and yaw, however, it is not capable ofmeasuring roll, i.e., rotation about the axis defined by the lensbarrel. Conventionally, two single-axis piezoelectric or quartzgyroscopes have been used with many external components to achieve thefull-scale range of image stabilization. InvenSense, Inc. provides anintegrated dual-axis gyroscope using MEMS technology for imagestabilization which offers smaller sizing.

While variable focusing, zoom and image stabilization features arepossible within a camera phone and other optical systems having arelatively small form factor, these features add substantially to theoverall mass of these devices. Further, due to the necessity of anextensive number of moving components, power consumption issignificantly high and manufacturing costs are increased.

Accordingly, it would be advantageous to provide an optical lens systemwhich overcomes the limitations of the prior art. It would beparticularly advantageous to provide such a system whereby thearrangement of and the mechanical interface between a lens and itsactuator structure were highly integrated so as to reduce the formfactor as much as possible. It would be greatly beneficial if such anoptical system involved a minimal number of mechanical components,thereby reducing the complexity and fabrication costs of the system.

SUMMARY OF THE INVENTION

The present invention includes optical lens systems and devices andmethods for using them. The systems and devices include one or moreelectroactive polymer-based (EAP) actuators integrated therein to adjusta parameter of the device/system. For example, the one or more EAPactuators may be configured to automatically adjust the focal length ofthe lens (auto-focusing), magnify the image being focused on by the lens(zoom), and/or adjust for any unwanted motion undergone by the lenssystem (image stabilization or shake prevention).

The one or more EAP actuators include one or more EAP transducers andone or more output members are integrated with one or more of a lensportion, a sensor portion and a shutter/aperture portion of the subjectlens systems/devices. The lens portion (i.e., the lens stack or barrel)includes at least one lens. In certain embodiments, the lens portiontypically includes a focusing lens component as well as an afocal lenscomponent. The sensor portion includes an image sensor which receivesthe image from the lens portion of the device for digital processing byimage processing electronics. Activation of the EAP actuators(s), i.e.,by the application of a voltage to the EAP transducer, adjusts therelative position of a lens and/or sensor component to effect or modifyan optical parameter of the lens system.

In one variation; an actuator assembly (including at least one EAPactuator) may be used to adjust the position of a portion of the lensstack along its longitudinal axis (Z-axis) relative to the sensorportion in order to change the focal length of the lens stack. Inanother variation, the same or different actuator may be used to adjustthe position of one or more lenses within the stack relative to eachother along the longitudinal axis (Z-axis) to adjust the magnificationof the lens system. Still yet, in another variation, an actuator may beused to move the sensor portion of the system portion within a planardirection (X-axis and/or Y-axis) relative to the lens portion, orvisa-versa, in order to compensate for unwanted motion imposed on thesystem, i.e., to stabilize the image imposed on the image sensor. Otherfeatures of the present invention include the use of an EAP actuator tocontrol the aperture size of a lens system and/or control the openingand closing of a shutter mechanism. An EAP actuator may provide only asingle function (e.g., shutter control or image stabilization) or acombination of functions (e.g., auto-focus and zoom).

The present invention also includes methods for using the subjectdevices and systems to focus and/or magnify an image, or to cancel outunwanted movement of the devices/systems. Other methods include methodsof fabricating the subject devices and systems.

These and other features, objects and advantages of the invention willbecome apparent to those persons skilled in the art upon reading thedetails of the invention as more fully described below.

BRIEF DESCRIPTION OF THE DRAWINGS

The invention is best understood from the following detailed descriptionwhen read in conjunction with the accompanying schematic drawings, wherevariation of the invention from that shown in the figures iscontemplated. To facilitate understanding of the invention description,the same reference numerals have been used (where practical) todesignate similar elements that are common to the drawings. Included inthe drawings are the following figures:

FIGS. 1A and 1B are a sectional perspective and exploded assembly views,respectively, of an optical lens system of the present inventionemploying an electroactive polymer actuator configured to provideauto-focusing;

FIGS. 2A and 2B provide schematic illustrations of an electroactivepolymer film for use with the optical systems of the present inventionbefore and after application of a voltage;

FIG. 3 is a sectional perspective view of another optical lens system ofthe present invention employing another type of electroactive polymeractuator for focus control;

FIGS. 4A and 4B are sectional perspective and exploded assembly views,respectively, of another optical lens system employing an actuatorcombination to control each of zoom and auto-focus;

FIGS. 5A and 5B are perspective views showing an alternative means ofcontrolling zoom;

FIGS. 6A-6C are perspective views showing progressive stages ofactuation of the transducer arrangement in FIGS. 5A and 5B;

FIGS. 7A and 7B are sectional perspective and exploded assembly views,respectively, of another optical lens system of the present inventionconfigured to provide auto-focusing and image stabilizationcapabilities;

FIG. 8 is an exploded assembly view of the image stabilization cartridgeof the lens system of FIGS. 7A and 7B;

FIGS. 9A and 9B are top and bottom planar views, respectively, of theelectrode configuration of the electroactive polymer transducer of theimage stabilization cartridge of FIG. 8;

FIGS. 10A and 10B are top and bottom planar views, respectively, ofanother embodiment of a framed electroactive polymer transducer usablewith the image stabilization cartridge of FIG. 8;

FIGS. 10C and 10D are top and bottom planar views, respectively, of theelectroactive films employed in the transducer of FIGS. 10A and 10B;

FIGS. 11A and 11B show the passive stiffness and load response,respectively, of the lens system of FIGS. 7A and 7B;

FIG. 12A is a perspective view of a leaf spring biasing member usablefor biasing an EAP auto-focus actuator of the present invention;

FIGS. 12B and 12C are perspective cross-sectional and top views of anoptical lens system of the present invention in which the leaf springbiasing member of FIG. 12A is in operative use;

FIG. 13 is a perspective cross-sectional view of another optical lenssystem of the present invention using an integrated leaf spring biasingmember;

FIGS. 14A and 14B are perspective cross-sectional views of a lens systemhousing with and without an associated lens barrel, respectively, havinganother type of integrated spring biasing member;

FIGS. 15A and 15B are perspective and cross-sectional views of anassembled lens barrel and flange assembly usable with the lens systemsof the present invention where the assembly provides an adjustablebarrel design for purposes of focus calibration;

FIG. 15C illustrates use of a tool for calibrating the infinity focusparameter of the lens barrel assembly of FIGS. 15A and 15B;

FIGS. 16A and 16B are perspective and cross-sectional views of anotherlens barrel assembly having an adjustable flange design for purposes offocus calibration;

FIGS. 17A and 17B are cross-sectional views of lens systems havingsingle-phase and two-phase actuator configurations, respectively, whichprovide a very compact, low-profile form factor;

FIGS. 18A and 18B are perspective and cross-sectional views of anexemplary EAP actuator-based lens displacement mechanism of the presentinvention;

FIGS. 19A and 19B are perspective and cross-sectional views,respectively, of another EAP lens displacement mechanism useable withthe present invention;

FIGS. 20A and 20B are perspective and cross-sectional views,respectively, of another lens displacement mechanism which employs EAPactuators and mechanical linkages;

FIG. 21 is a cross-sectional view of another hybrid lens displacementsystem of the present invention;

FIGS. 22A and 22B are perspective and cross-sectional views,respectively, of an “inchworm” type of lens displacement mechanism ofthe present invention;

FIGS. 23A and 23B are perspective and cross-sectional views,respectively, of a multi-stage “inchworm” type of lens displacementmechanism of the present invention;

FIG. 24A is a schematic illustration of cross-section of an actuatorcartridge of the lens displacement mechanism of FIGS. 23A and 23B;

FIGS. 24B-24F schematically illustrate various positions of the actuatorand associated lens guide rail during an actuation cycle;

FIGS. 25A-25C are cross-sectional views of a multi-actuator lensdisplacement system of the present invention;

FIGS. 26A and 26B are cross-sectional views of inactive and activestates of lens image stabilization system of the present invention;

FIGS. 27A-27C are cross-sectional views of another lens imagestabilization system of the present invention in various activationstates;

FIG. 28 is an exploded view of an aperture/shutter mechanism of thepresent invention which is suitable for use with the subject lenssystems as well as other known lens systems;

FIG. 28A is a side view of the rotating collar of the shutter/aperturemechanism of FIG. 28;

FIGS. 29A-29C show the aperture/shutter mechanism of FIG. 28 in fullyopened, partially open and fully closed states, respectively;

FIGS. 30A and 30B are cross-sectional views of a unimorph actuator filmfor use in the lens displacement mechanisms of the present invention;

FIGS. 31A and 31B illustrate side views of another lens displacementmechanism of the present invention in inactive and active states,respectively, employing the unimorph actuator film of FIGS. 30A and 30B;

FIGS. 32A and 32B illustrate side views of another lens displacementmechanism of the present invention which employs a unimorph actuator;

FIGS. 33A and 33B illustrate the use of EAP actuator having featureswhich function to address certain conditions, e.g., humidity, of theambient environment in which the lens system is operated in order tooptimize performance;

FIG. 34 shows a cross-sectional view of a lens displacement system ofthe present invention employing another configuration for addressingambient conditions:

FIGS. 34A and 34B are perspective and top views of a the ambientcondition control mechanism of the system of FIG. 34;

FIG. 35 shows a cross-sectional view of another lens displacement systemof the present invention having a lens position sensor;

FIG. 36A is a perspective view of another variation the mechanicalcomponentry of a shutter/aperture mechanism of the present invention;

FIGS. 36B and 36C illustrate the shutter/aperture of FIG. 36A in fullyopen and fully closed states, respectively; and

FIG. 36D is a perspective view of the mechanism of FIG. 36A operativelycoupled with an EAP actuator of the present invention; and

DETAILED DESCRIPTION OF THE INVENTION

Before the devices, systems and methods of the present invention aredescribed, it is to be understood that this invention is not limited toa particular form fit or applications as such may vary. Thus, while thepresent invention is primarily described in the context of a variablefocus camera lens, the subject optical systems may be used inmicroscopes, binoculars, telescopes, camcorders, projectors, eyeglassesas well as other types of optical applications. It is also to beunderstood that the terminology used herein is for the purpose ofdescribing particular embodiments only, and is not intended to belimiting, since the scope of the present invention will be limited onlyby the appended claims.

Referring now to the drawings, FIGS. 1A and 1B illustrate an opticallens system of the present invention having auto-focus capabilities. Thefigures detail a lens module 100 having a lens barrel 108 holding one ormore lenses (not shown). An aperture 106 is provided at a distal orfront end of lens barrel 108. Positioned distally of aperture 106 is anelectroactive polymer (EAP) actuator 102 having an electroactive polymerfilm 120. Film 120 sandwiched about its periphery by frame sides 122 a,122 b and centrally by disc sides 104 a, 104 b, leaving an exposedannular section of film 120. The structure and function of theelectroactive films are now discussed in greater detail with referenceto FIGS. 2A and 2B.

As illustrated in the schematic drawings of FIGS. 2A and 2B,electroactive film 2 comprises a composite of materials which includes athin polymeric dielectric layer 4 sandwiched between compliant electrodeplates or layers 6, thereby forming a capacitive structure. As seen inFIG. 2B, when a voltage is applied across the electrodes, the unlikecharges in the two electrodes 6 are attracted to each other and theseelectrostatic attractive forces compress the dielectric layer 4 (alongthe Z-axis). Additionally, the repulsive forces between like charges ineach electrode tend to stretch the dielectric in plane (along the X- andY-axes), thereby reducing the thickness of the film. The dielectriclayer 4 is thereby caused to deflect with a change in electric field. Aselectrodes 6 are compliant, they change shape with dielectric layer 4.Generally speaking, deflection refers to any displacement, expansion,contraction, torsion, linear or area strain, or any other deformation ofa portion of dielectric layer 4. Depending on the form fit architecture,e.g., the frame in which capacitive structure is employed, thisdeflection may be used to produce mechanical work. The electroactivefilm 2 may be pre-strained within the frame to improve conversionbetween electrical and mechanical energy, i.e., the pre-strain allowsthe film to deflect more and provide greater mechanical work.

With a voltage applied, the electroactive film 2 continues to deflectuntil mechanical forces balance the electrostatic forces driving thedeflection. The mechanical forces include elastic restoring forces ofthe dielectric layer 4, the compliance of the electrodes 6 and anyexternal resistance provided by a device and/or load coupled to film 2.The resultant deflection of the film as a result of the applied voltagemay also depend on a number of other factors such as the dielectricconstant of the elastomeric material and its size and stiffness. Removalof the voltage difference and the induced charge causes the reverseeffects, with a return to the inactive state as illustrated in FIG. 2A.

The length L and width W of electroactive polymer film 2 are muchgreater than its thickness t. Typically, the dielectric layer 4 has athickness in range from about 1 μm to about 100 μm and is likely thickerthan each of the electrodes. It is desirable to select the elasticmodulus and thickness of electrodes 6 such that the additional stiffnessthey contribute to the actuator is generally less than the stiffness ofthe dielectric layer, which has a relatively low modulus of elasticity,i.e., less than about 100 MPa.

Classes of electroactive polymer materials suitable for use with thesubject optical systems include but are not limited to dielectricelastomers, electrostrictive polymers, electronic electroactivepolymers, and ionic electroactive polymers, and some copolymers.Suitable dielectric materials include but are not limited to silicone,acrylic, polyurethane, flourosilicone, etc. Electrostrictive polymersare characterized by the non-linear reaction of electroactive polymers.Electronic electroactive polymers typically change shape or dimensionsdue to migration of electrons in response to electric field (usuallydry). Ionic electroactive polymers are polymers that change shape ordimensions due to migration of ions in response to electric field(usually wet and contains electrolyte). Suitable electrode materialsinclude carbon, gold, platinum, aluminum, etc. Suitable films andmaterials for use with the diaphragm cartridges of the present inventionare disclosed in the following U.S. Pat. Nos. 6,376,971, 6,583,533,6,664,718, which are herein incorporated by reference.

With reference again to FIGS. 1A and 1B, the operative engagement of EAPactuator 102 with lens barrel and stack 108 enables auto-focusing of thelens assembly. Frame 122 is affixed to a distal end of a housing 114 bymeans of bolts 126 a which are received in holes 126 b, while disc orcap portion 104 of the EAP actuator 102 is positioned or mounted againstthe distal end of lens barrel 108, whereby an aperture 118 within cap104 is axially aligned with aperture 106 to allow for the passage oflight to the lens assembly. A biasing member in the form of leaf springmechanism 110 is operatively engaged between lens barrel 108 and frame122 to pre-load or bias disc 104 in the direction of arrow 125 toprovide a frustum-shaped architecture. Such frustum-type actuators aredescribed in detail in U.S. patent application Ser. Nos. 11/085,798,11/085,804 and 11/618,577, each incorporated by reference in itsentirety. Pre-loading or biasing insures that actuator 102 actuates inthe desired direction rather than simply wrinkle upon electrodeactivation. With the illustrated leaf spring mechanism 110, housing 114may be provide with wall recesses 132 or the like to accommodate andoperatively position one or more leaf springs relative to the actuator102. Other biasing means such as simple positive rate springs (e.g.,coil spring) as shown in FIG. 7A may alternatively be used.

On the proximal or back side of lens assembly or stack 108 is an imagesensor/detector 116 (such as a charge-couple device (CCD)) whichreceives the image for digital processing by control electronics 128(shown in FIG. 1B only). The focal length of lens stack 108 isadjustable by the selective actuation of EAP actuator 102 (where theaxial position of one or more lenses is adjusted relative to the otherlenses). Sensor 116 as well as actuator 102 may be powered viaelectrical coupling to power supply 130.

As shown in FIG. 1B, a completed camera assembly will include at least ashroud or cover 112. Other components, such an infrared (IR) filter (notshown), commonly used with conventional lens systems, may also beoperatively incorporated into system 100.

FIG. 3 illustrates another lens module 140 of the present invention.Cylindrically-shaped lens barrel 142, having one or more lenses 144, ismovably held within outer and inner housing members 146, 148 with adistal portion 142 a slidably positioned through an opening in outerhousing 146 and a proximal portion 142 b slidably positioned through anopening in inner housing 148. The juncture between distal and proximalbarrel portions 142 a, 142 b defines an annular shoulder 150 to which anannular inner frame member 158 of EAP actuator 152 is mounted. Actuator152 has a double-frustum architecture with each frustum defined by afilm 154 a, 154 b held in a stretched condition between inner framemember 158, with the peripheral portion of distal film 154 a heldbetween outer housing 146 and frame block or spacer 156, and aperipheral portion of proximal film 154 b held between inner housing 148and frame block 156. Instead of being biased by a leaf spring mechanism,the distal film 154 a of the double frustum structure provides thepreload for actuator 152 in the direction of arrow 155, thereby movinglens barrel 142 in the same direction to adjust the focal lens 144.While the unbiased film 154 b is an EAP film, the biased film 154 a neednot be, and may simply be an elastomeric webbing. Should film 154 acomprise an electroactive polymer material, however, it may be employedfor sensing position by capacitance change or may, collectively withfilm 154 b, provide a two-phase actuator. In the latter case, when film154 b is activated, it causes lens barrel 142 to move in the directionof arrow 157, thereby adjusting the focal length of lens 144 in theopposite direction.

In another variation of the invention, FIGS. 4A and 4B show an opticalsystem 160 employing an actuator combination to control each of focusand zoom. The system has a focus stage housed within housing 182 andincludes focusing lens 164 held within lens barrel 162 and driven by adiaphragm actuator 166. Focusing is adjusted by varying the distancebetween lens 164 and image sensor 180 in a manner similar to thatdescribed with respect to FIGS. 1A and 1B. System 160 also provides azoom stage which includes a zoom lens 168 held within lens fixture 170and under lens cover 176 which is mechanically coupled to a pair ofplanar actuators 172 a, 172 b by way of armatures 174 a, 174 b,respectively. Each of these actuators 172 a, 172 b is formed bystretching EAP film over or upon a common frame element 178 affixed tothe armatures. Zoom function is accomplished by varying the distancebetween lens 164 and lens 168. Generally focus adjustment requiresbetween about 0.1 and 2.0 mm of movement; while zoom often requiresabout 5 to 10 times that amount of stroke. Though not shown, it also iscontemplated that multiple faces of a combined frame may carry diaphragmactuators alone or planar actuators alone. Still further, non-orthogonalframe geometry may be employed.

In cases where there is more available space, it may be desirable toprovide an EPAM zoom/focus engine suitable for longer zoom travel toincrease the operating range of the device. FIGS. 5A and 5B areperspective views showing an alternative lens system 190 in which atelescopic arrangement of paired sets of planar actuators 192 a, 192 b,where one of each pair is positioned on opposite sides of a lenscarriage 194 which is fixed to lens barrel 196 which carries zoom lens198. When actuated, the planar actuator arrangement translates lensbarrel 196 and zoom lens 198 along the focal axis relative to an imagesensor 200 in the directions of arrows 202 and 204, where FIGS. 5A and5B show minimum and maximum zoom positions, respectively.

The manner in which the actuators are connected and operate is clarifiedby the enlarged section views of FIGS. 6A-6C which illustrate variousactuation stages of an actuator stack of FIGS. 5A and 5B. Theprogressive motion is achieve by connection of successive output bars208 to actuator frame sections 206 with the innermost output barattached to a rod 210 to drive zoom components.

Turning now to FIGS. 7A and 7B, there is shown another optical lenssystem 300 of the present invention which provides image stabilizationcapabilities in addition to auto-focusing. Lens module 302 includes alens barrel 312 which holds one or more lenses and, here, is shown tohave four lenses 314 a, 314 b, 314 c and 314 d, but fewer or more lensesmay be employed. Lens assembly 314 is displaced by an EAP actuator 320having an EAP film 325 extending between an outer frame 322 and an innerdisc or cap member 328. Outer frame 322 is fixed between bottom housing324 and top housing 326. A biasing member in the form of coil spring 332is positioned about lens barrel 312 and operatively engaged between theback end 334 of bottom housing 324 and a shoulder or flange 336 of lensbarrel 312, thereby pre-loading or biasing cap or disc 328 in thedirection of arrow 335 to provide a frustum-shape to EAP actuator 320.

The radial rigidity of the actuator's disc member 328 and thecounter-force/bias (opposite that of arrow 335) imposed on the distalend of lens barrel 312 assist in maintaining the concentricity of thebarrel within the lens module 302. Moreover, the overall structure ofthe biased EAP actuator effectively suspends the lens barrel, making itunaffected by gravity, as evidenced by the graph of FIG. 11A which showsthe passive stiffness of such a lens positioning system. FIG. 11B, onthe other hand, illustrates the normal load response of the system afterinitiation of travel from the hard stop position.

A bushing wall 318 extends upward from the back end 334 of housing 324and is seated between coil spring 332 and the outer surface of lensbarrel 312. Bushing 318 acts as a linear guide for lens barrel 312 and,together with flange 336, provides a travel stop at a maximum “macro”(near) focus position. Having a built-in travel or hard stop is alsouseful upon initial calibration of the barrel's position duringmanufacturing assembly of system 300. The rigidity of bushing wall 318also provides added crush protection to the lens assembly during normaluse. Additionally, the overall structure of the EAP actuator 320provides some shock absorbency for the lens barrel. Collectively, theEAP actuator, the bias spring, the bushing and the overall barrel designprovide a uniform radial alignment for optimal performance of the lenssystem.

The frustum architecture of the EAP actuator may be provided by othertypes of biasing members, such as the leaf spring biasing mechanism 390illustrated in FIG. 12A, which configuration provides a particularly lowprofile. Biasing mechanism 390 includes an annular base 392 havingradially-extending, forked tabs 394 spaced about and angled upward fromthe circumference of base 392 at flexure points 396. FIGS. 12B and 12Cshow the leaf spring biasing mechanism 390 operatively employed as abiasing member within an optical lens system having a construct similarto that of system 300 of FIGS. 7A and 7B. The base portion 392 of theleaf spring encircles lens barrel 312 under flange 336 and each of theforked tabs 394 engage the underside of outer frame 322 which acts as abearing surface. To provide a uniformly balanced, concentric bias, theleaf spring mechanism preferably provides at least three, evenly-spacedtabs 394. Further, to prevent unintentional rotational movement of leafspring 390, the tines or legs of the forked tabs 394 within slotslocated at each corner of the housing. An inner housing block 398 actsas a linear bushing or backstop to lens barrel 312 when in the“infinity” (i.e., most proximal) position.

The biasing member may also be integrated into the lens barrel and/orhousing structure of the optical lens system. FIG. 13 illustrates anexample of such where a structural portion 410 of a lens system of thepresent invention includes a lens barrel 412 concentrically positionedwithin a housing component 414. A bias member 416 is positioned inbetween and straddles across the lens barrel and housing, where thebiasing member may be formed with these components as a unitary ormonolithic structure (e.g., by means of molding) or otherwise beprovided as an insert therebetween. The latter configuration isillustrated where an annular diaphragm 418 having a convex configuration(from a top or outside perspective); however, a concave configurationmay alternatively be employed. Silicone, polyurethane, EPDM, otherelastomers or any low viscosity elastomer is a suitable material fordiaphragm 418. The diaphragm, extends between inner and outer side walls420 a, 420 b which brace against the outer lens barrel wall and innerhousing wall, respectively. The curved diaphragm 418 provides a springmechanism which has a negative rate bias. Other examples of EAPactuators having a negative rate bias are disclosed in previouslyreferenced U.S. patent application Ser. No. 11/618,577.

FIGS. 14A and 14B illustrate other ways of integrating the actuator'sspring bias into the subject lens systems. In FIG. 14A, the spring biasto be applied to the EAP actuator (not shown) is provided by two or moretabs 422 which are structurally integrated into the bottom housing 324of, for example, lens system 30Q of FIGS. 7A and 7B, and extend radiallyinward within the concentric gap between the outer wall of housing 324and bushing wall 318. Tabs 422 are bent or molded in a manner so as toprovide a spring bias when a load is applied. The lens barrel 312 mayalso be integrally formed (such as by molding) with and fixed to tabs422, as shown in FIG. 14B.

The lens systems of the present invention may be equipped with one ormore light filters at any suitable position relative to the lenses.Referring again to system 300 of FIGS. 7A and 7B, top housing 326 has atransparent or translucent cover 330 positioned therein for passinglight rays. Alternatively, the entirety of top housing 326 may be moldedfrom the transparent/translucent material. In either case, the cover mayfunction as a filter which prevents infrared wavelengths of about 670 nmand greater from being transmitted through the lens assembly whileallowing visible wavelengths to be transmitted generally without loss.Alternatively or additionally, an IR filter 366 may be positionedproximally of the lens assembly.

The lens system of the present invention may also have imagestabilization capabilities. With reference again to FIGS. 7A and 7B,positioned proximally of lens module 302 is an exemplary embodiment ofan image stabilization module 304, which includes an image sensor 306for receiving images focused onto it by lens module 302 and associatedelectronics for processing those images. Image stabilization module 304also include an EAP actuator 310 which serves to compensate for anymovement, i.e., “shake”, of image sensor 360 in the x-y plane in orderto keep the focused image sharp. Z-axis correction may also be providedalong with a sensor for sensing such motion.

EAP actuator 310 has a planar configuration comprising a two-ply EAPfilm transducer having “hot” and ground sides 338 and 348, bestillustrated in the exploded assembly view of FIG. 8 and the planar viewsof FIGS. 9A and 9B. EAP film 338 comprises elastomeric layer 342 andelectrically isolated electrodes 340 which each extend over a portion ofelastomer 342 while leaving a central portion 362 a of layer 342 free ofelectrode material. EAP film 348 includes elastomeric layer 352 and asingle ground electrode 350. The annular shape of ground electrode 350enables apposition to each hot electrode 340 and leaves a centralportion 362 b free of electrode material which matches that of portion362 a of film 338. Collectively, the two films provide a transducerhaving four active quadrants (i.e., having four active-ground electrodepairs) to provide a four-phase actuator; however, more or fewer activeportions may be employed, as discussed below with respect to FIGS.10A-10D. Each quadrant is selectively activated, either individually orin tandem with one or more of the other quadrants to provide a range ofactuation motion in the x-y plane (i.e., with two degrees of freedom),in response to and to compensate for shake undergone by the system.Sandwiched between the two films are electrical tabs 344, one for eachhot electrode. A pair of grounded electrical tabs 346 is provided onopposing outer surfaces of EAP films 338, 348. Tabs 334 and 348 are forcoupling the EAP actuator to a power supply and control electronics (notshown). The two-ply transducer film is in turn sandwiched between topand bottom frame members 354 a, 354 b which hold the EAP films instretched and strained conditions.

Actuator 310 also includes two disks 356, 358, one centrally positionedon each side of the composite film structure. The disks serve variousfunctions. Disk 356, provided on the outer side of hot electrode film338, is held in planar alignment within the annular space or cut-out offrame side 354 b by backing plate or cover 360 b. Disk 356 acts as atravel stop—preventing film 338 from contacting the back plate and actsas a supplemental bearing support to the sensor. Disk 358 is provided onthe outer side of film 348 and held in planar alignment within theannular space of cut-out of frame side 354 a by front plate or cover 360a which also has a cut-out portion through which disk 358 transfersmovement of actuator 310 to image sensor 306. To facilitate transmissionof the output actuator motion from disk 358 to image sensor 306, alinear bearing structure/suspension member 308 is provided therebetween.Structure/member 308 is in the form of a planar substrate 362 having aplurality of shock absorbing elements 364, e.g., spring tabs extendingfrom the edges of substrate 362, which function as shock absorbers tooptimize the output motion of actuator 310. Substrate 362 may be in theform of a flex circuit with the spring tabs 364 (when made of conductivematerial) providing electrical contact between image sensor 306 and itsassociated control electronics to actuator 310.

Collectively, image sensor 306, suspension member 308 and actuator 310are nested together within a housing 316. Housing 316 is recessed on adistal side 368 to receive lens module 302. On its proximal side 370,housing 316 has notches or recesses 372 for accommodating electricalcontact tabs 344, 346 of actuator 310 and/or spring tabs 364 ofbearing/suspension member 308.

As mentioned above with respect to discussion of the four-phase actuator310, the image stabilization actuators of the present invention may haveany number of active areas which provide the desired phased actuation.FIGS. 10A-10D illustrate a three-phase EAP actuator 380 suitable for usewith the subject optical lens systems of the present invention for atleast image stabilization. Actuator 380 has a hot EAP film 384 a havingthree electroded areas 386, each of which effects actuation ofapproximately one-third of the active area of actuator 380. Grounded EAPfilm 384 b has a single annular ground electrode 388 which, whenpackaged with film 384 a by frame sides 382 a and 382 b, provides theground side for each of the three active portions of actuator 380. Whilethis three-phase design is more basic, both mechanically andelectrically, than the four-phase design, more complex electroniccontrol algorithms are necessary as a three-phase actuator may not aloneprovide discrete movement in either the X or Y axes.

Many manufactured hardware components have dimensions which fall withinan acceptable tolerance range, whereby fractional dimensional variationsamongst like components and between associated components do not affectproduction yields. However, with devices such as optical lenses, moreprecision is often necessary. More specifically, it is important thatthe position of the lens assembly relative to the image sensor be set tooptimize the focus of the lens assembly when in the “infinity” position(i.e., when in an “off” state) so as to ensure accurate focusing when inuse by the end user. As such, the infinity position is preferablycalibrated during the fabrication process.

FIGS. 15A and 15B illustrate an exemplary design configuration forcalibrating the infinity position of the lens assembly, i.e., adjustingthe distance between the image sensor and the lens assembly to establishan optimally focused infinity position, during the fabrication process.The lens barrel assembly 430 is comprised of lens barrel 432 and aseparable flange 434. Flange 434 is internally threaded 439 torotationally engage with external threads 437 of lens barrel 432. Flange434 is provided with a radially extending tab 436 which, when placedwithin the system housing 442, as shown in FIG. 15C, protrudes from adesignated opening 436. As such, the rotational position of flange 434is fixed relative to lens barrel 432. The crest portion 438 of the topcover 435 of the lens barrel 432 is provided with grooves orindentations 440 for receiving the working end 446 of a calibration tool444, as shown in FIG. 15C. Tool 444 allows access to lens barrel 432even after enclosed within housing 442, and is used to rotate the lensbarrel 432 in either direction relative to the threadedly engaged flange434, the position of which is fixed within the housing by means of tab436 and opening 436. This relative rotational movement, in turn,translates the entire lens barrel assembly 430 linear or axiallyrelative (in either direction depending on rotational direction of lensbarrel) to the image sensor (not shown) and other fixed componentswithin the lens system. It is the distance between the lens assembly 448(see FIG. 15B) and the image sensor that defines the infinity positionof the system.

FIGS. 16A and 16B illustrate another lens barrel configuration 450 forpurposes (at least in part) of calibrating a lens assembly. Thedifference with respect to the configuration of FIGS. 15A-15C is thatflange 456 is movable relative to the lens barrel which is rotationallyfixed when operatively seated within housing 452. This fixation isprovided by a bumper or protrusion 460 extending radially from the lensbarrel's outer wall. When the lens barrel is seated within the systemhousing 452, bumper 460 is positioned within an opening or window 458within the housing wall, which prevents rotational movement of the lensbarrel. The outer circumference of flange 456 is provided withindentations 462 which are configured to engage with a calibration tool(not shown). Housing 452 is provided with a window 464 through which theperipheral edge of flange 456 is exposed. By use of calibration a tool(or a finger if possible), flange 456 is rotatable in either direction,as needed. As with the previously described configuration, the relativemovement of the flange to the lens barrel linearly/axially translatesthe entire lens assembly relative to the image sensor (not shown). Bothconfigurations provide a convenient and easy way to calibrate theinfinity position of the lens assembly during final assembly of the lenssystem.

FIGS. 17A and 17B illustrate two other embodiments of lens systems ofthe present invention having more simplistic and lower profile designsin which a lens 472 (either a single lens or the distal most lensamongst a plurality of lenses) is directly integrated with andselectively positioned by an EAP actuator.

Lens system 470 of FIG. 17A employs a single-phase actuator comprisinginner and outer frame members 474, 476, respectively, with an EAP film478 stretched therebetween. Lens 472 is positioned and fixedconcentrically within inner frame 474 such that the output movement bythe actuator is directly imposed on lens 472. The single-phase actuatoris biased in the direction toward the front side 472 a of the lens by acompact coil spring 480 positioned within the frustum space definedbetween inner frame 476 and a back plate 482. The latter acts as hardstop at a maximum “macro” (near focus) position. When the actuator is inthe “off” state, lens 472 is in the macro position and, when activated,the lens moves toward the infinity position in the direction of arrow488. In lens positioner applications which only operate in the macroposition, an initial macro setting improves the reliability of thesystem by eliminating unnecessary displacement range.

A two-phase lens system 510 having a similar, low-profile construct isillustrated in FIG. 17B. Here, the EAP actuator comprises two layers ordiaphragms which act to bias each other. The top or back actuatorincludes EAP film 494 extending between inner and outer frames 490 a,490 b and the bottom or front actuator includes EAP film 496 extendingbetween inner and outer frames 492 a, 492 b. The inner frames 490 a, 492a are coupled together while the respective outer frames 490 b, 492 bare spaced apart by an intermediate housing member 500 and sandwichedbetween it and, respectively, top housing member 498 and bottom housingmember 502. Lens 472 (having a truncated, low-profile shape) ispositioned concentrically within the coupled inner actuator frames. Withtwo active actuators, each provides the bias for the other and allowstwo-phase or bid-directional movement of lens 472. Specifically, whenthe bottom actuator is activated while the top actuator is off, the biasby the top actuator moves lens 472 in the direction of arrow 504 and,likewise, when the top actuator is activated while the bottom actuatoris off, the bias by the bottom actuator moves lens 472 in the directionof arrow 506. This enables lens 472 to have double (2×) the traveldistance as that of the single-phase system 470. This double diaphragmconfiguration can be made to function as a single-phase actuator bymaking one or the other of the actuators passive, i.e., always in theoff state. In either case, the double diaphragm actuator provides a verylow profile form factor for the lens system.

Lens travel/stroke, whether for auto-focusing or zooming, can beincreased (as well as decreased) by employing additional structuralcomponents which enable lens movement. This movement may involveabsolute displacement of a single lens or a stack of lenses and/orrelative movement between lenses within an assembly of lenses. Theadditional components for effecting such movements may include one ormore EAP actuators, mechanical linkages or the like, or a combination ofboth, which are integrated with or coupled to the lens barrel/assembly.

FIGS. 18 and 19 provide perspective views of exemplary lens displacementmechanisms of the present invention in which a number of EAPactuator/transducers are stacked in series to amplify stroke output.illustrated by arrows 525, 535, respectively. As illustrated, thetransducers may be coupled or ganged together in a desired configurationto achieve the desired output.

The lens displacement mechanism 520 of FIGS. 18A and 18B provides anumber of double-frustum EAP actuator 528 units in which each actuatorunit 528 includes two concave-facing transducers diaphragms 526 havingtheir inner frames or caps 532 ganged together. In turn, the outerframes 534 of the actuators are ganged or coupled to an outer frame 534of an adjacent actuator. The distal most outer frame 534 a is mounted toa lens frame 524 having lens 522 positioned therein. The proximal mostouter frame 534 b is positioned distally of an image sensor module (notshown).

FIGS. 19A and 19B illustrate a similarly functioning lens displacementmechanism 540 where each of the plurality of EAP actuators units 548have an inverted configuration whereby the transducer diaphragms 544have their concave sides facing inward with their outer frames 538ganged together. In turn, the inner frames 536 of the actuators areganged or coupled to an inner frame 536 of an adjacent actuator. Thedistal most inner frame 536 a serves to hold lens 542 concentricallytherein. The proximal most inner frame 536 b is positioned distally ofan image sensor module (not shown)

With either design, the greater the number of actuator levels, thegreater the stroke potential. Further, one or more the actuator levelswithin the stack may be used for zoom applications where additionallenses may be integrated with the various actuator levels, andcollectively operated as an afocal lens assembly. Additionally oralternatively, one or more of the transducer levels may be setup forsensing—as opposed to actuation—to facilitate active actuator control oroperation verification. With any of these operations, any type offeedback approach such as a PI or PID controller may be employed in thesystem to control actuator position with very high accuracy and/orprecision.

Referring now to FIGS. 20A and 20B, there is illustrated another lensdisplacement mechanism 550 utilizing EAP-based portion or components 552in conjunction with a mechanical lens driving portion or components 554,whereby the former is used to drive the latter. EAP portion 552 includesa double-frustum actuator in which the outer frames 556 a, 556 b areheld between bottom housing portions 558 a, 558 b with inner frames 555a, 555 b of the coupled transducers being relatively translatable alongthe optical axis 576. As discussed above, the actuator may be configuredas either a two-phase actuator which enables active movement in bothdirections along optical axis 576, or as a single-phase actuator movablein the upward/forward direction along the optical axis.

Mechanical portion 554 of displacement system 550 includes first andsecond driver plates or platforms 560, 564 interconnected by linkagepairs 566 a, 566 b and 568 a, 568 b. Each of the plates has a centralopening to hold and carry a lens (not shown) which, collectively,provide an afocal lens assembly which, when moved along the focal axis,adjusts the magnification of the focal lens (not shown), which iscentrally-disposed in lens opening 578 within top housing 574. Whileonly two zoom displacement plates are provided, any number of plates andcorresponding lenses may be employed.

The linkage pairs provide a scissor jack action to move the seconddriver plate 564 along the optical axis in response to a force enactedon the first driver plate 560. As understood by those skilled in theart, such a scissor jack action translates the second driver plate 564at a greater rate than first driver plate 560, where the translationratio between the first plate and second plate to provide a telescopingeffect. Plates 560, 564 are slidably guided along and by linear guiderods 572 which extend between bottom housing portion 558 a and tophousing 574. Upon activation of actuator portion 552, cap 555 a isdisplaced thereby applying an upward force against the proximal end 562of driver plate 560. This drives first plate 560 which in turn moves thelinkage pairs to drive second plate 564 at a selected greater rate oftranslation. While scissor jack linkages are illustratively described,other types of linkages or mechanical arrangements maybe used totranslate one plate at a proportionately greater translation rate anddistance than the other plate.

FIG. 21 provides a cross-sectional view of another hybrid(actuator-linkage) lens displacement mechanism 580 of the presentinvention in which the actuator portion 582 includes a single EAPtransducer 584 biased upward along the optical axis 588 by a coil spring586, however, any spring bias means (e.g., leaf spring) may be employed.Upon activation of the actuator, cap 590 moves against first driverplate 592 which drives the linkage mechanism 596 to then move seconddriver plate 594 upward along optical axis 588.

Referring now to FIGS. 22A-22B and 23A-23B, there are illustrated twoother lens displacement mechanisms of the present invention which employa hybrid construct. Both of these mechanisms translate their respectivelens assemblies/barrels in an incremental or “inchworm” fashion by useof two types of actuator mechanisms.

The lens displacement mechanism 600 of FIGS. 22A and 22B employs twotypes of actuation motion to effect the inchworm displacement of a lensassembly/barrel 602—“thickness mode” actuation and in-plane actuation.The lens barrel 602 holds one or more lenses (not shown) which may formafocal lens assembly for zooming purposes. Barrel 602 has bushings 606extending laterally from an outer surface. Bushings 606 are frictionallyand slidably engaged with guide rails 604 which extend between top andbottom actuation portions 608 a, 608 b. The actuation components ofmechanism 600 include a bottom portion 608 a and a top portion 608 b.Each actuation portion includes an actuator stack having a thicknessmode actuator EAP film 610 and a planar actuator EAP film 612. The filmsare separated from each other and encapsulated between layers offlexible material 614 a-614 c, such as a visco-elastic material andpreferably with a very low viscosity and durometer rating, to form theactuator stack 608 a. FIG. 22A shows the electrode layer patterns 610 aand 612 a, respectfully, in the cutaway views of actuator stack 608 a. Acentral hole or aperture 616 extends through stack 608 a to allowpassage of the image focused upon to an image sensor/detector (notshown).

In operation, with the back or bottom ends 604 a of the guide railsengaged with film stack 608 a (or at least with actuator layers 614 b,614 c) at substantially right angles, activation of planar actuator EAPfilm 612 causes rail ends 604 a to move laterally in opposingdirections, e.g., apart, from each other in a direction 605perpendicular to the axial length of guide rails 604. With the front ortop ends 604 b of the guide rails in a fixed position, this movementcauses the guide rails 604 to bear against bearings 606 therebyfrictionally securing the position of lens barrel 602 on rails 604.Deactivation of film 612 draws the rails back to their neutral or rightangle position with respect to film stack 608 a. Thickness modeactuation is then employed to translate guide rails 604 in an axialdirection 607 thereby translating lens barrel 602, now frictionallyengaged to guide rails 603, in the same direction to adjust the focallength of the lens assembly. More specifically, when EAP film 610 isactivated, film stack 608 a buckles thereby axially displacing guiderails 604. Upon advancement of lens barrel 602, a frictional bearingsurface (not shown) is positioned to engage the outer surface of thebarrel whereby this frictional engagement is greater than the frictionalengagement imposed by the barrel bushings 606 on rails 604. Thefrictional engagement of the bearing surface on the walls of the barrelovercomes that of the bushings on the guide rails, such that, when thethickness mode EAP film 610 is deactivated and the guide rails return tothe inactive position, the lens barrel is retained in the advancedposition. The planar-thickness mode actuation sequence just describedmay be reversed to translate the lens assembly in the opposite axialdirection.

Optionally, a top actuation portion 608 b may be employed to adjust therelative position or angle of rails 604 and/or to increase the potentialtravel distance of lens barrel 602 in either axial direction 607.Actuator 608 b, in this example, is constructed to provide planaractuation for adjusting the position of the rails for the purpose offrictionally engaging them against bushings 606. In particular, actuatorstack 608 a comprises a planar actuation EAP film 618 sandwiched betweenlayers 620 a, 620 b, which may be made of the same material as layers614 a-614 c of bottom actuator 608 a. The composite structure has a holeor aperture 622 extending therethrough to allow for the passage of lightrays passed through a focusing lens (not shown) to the zoom or afocallens assembly 602. Preferably, the planar sections of 608 a and 608 bactuate simultaneously to maintain the guide rods 604 in a parallelrelationship with each other.

Top actuator 608 b may be employed in lieu of the planar actuation ofbottom actuator 608 a to provide the angular displacement of the railsas described above, or it may be used in tandem with the planaractuation portion of bottom actuator 608 a to laterally displace bothends of the rails. This tandem actuation can be controlled to preciselyadjust the angular disposition of the rails or, alternatively, tomaintain the rails at right angles with respect to the planar surfacesof the respective actuators (i.e., the rails are maintained parallel toeach other) but provide a sufficient lateral displacement (eithertowards or away from lens barrel 602) to effect frictional bearingagainst bushings 606. Top actuator 608 b may also be equipped withthickness mode actuation capabilities as described above to effectamplified axial movement of the guide rails. While translation of bothrails has been described, the present invention also includes variationsof lens displacement mechanisms which are configured to move only asingle rail or more than two.

FIGS. 23A and 23B illustrate another lens displacement mechanism 625that employs an inchworm type of actuation motion. Mechanism 625 housesa lens assembly containing a plurality of lens stages 626 a, 626 b, 626c, 626 d, each having a cutout 627 for retaining a lens (not provided).Those skilled in the art will appreciate that fewer or more stages thanthe four illustrated may be employed, and that the stages may retainlenses used for focusing, zooming, or merely provide a pass through forlight rays. Further, not all stages need to be translatable, and may befixed to the mechanism housing or struts 628. In the illustratedvariation, for example, the first and fourth stages 626 a, 626 d arefixed, while the second and third stages 626 b, 626 c are translatable.The four lens stages are held in spaced parallel alignment with eachother by linear guide rails 642 which are fixed to and extend betweenthe top to the bottom lens stages 626 a, 626 d. The movable lens stages626 b, 626 c are linearly translatable along the guide rails 642 throughbearings 648.

The actuation portion of the displacement mechanism 625 includesfirst/top and second/bottom actuator cartridges 630 a and 630 b. Theconstruct of cartridge 630 a is illustrated in FIG. 24A, wherein twoactuators are provided—a single-phase linear actuator 632 and two-phaseplanar actuator 634 stacked in series with each other. Each actuatorcomprises an EAP film extending between inner and outer members 638 a,638 b, whereby the respective inner members 638 a are ganged togetherand the respective outer members 638 b are coupled to a spacer 640positioned therebetween. In the illustrated variation, the EAP film ofeach planar actuator 634 is divided into at least two separatelyactivatable portions 636 a, 636 b to provide two-phase (or more)actuation. Each linear actuator 632, in this variation, has a monolithicEAP film 636 c which is activatable in whole. The two single-phaselinear (from each of the top and bottom cartridges) actuators 632collectively form a two-phase linear actuator, wherein the bottom linearactuator is biased by the top linear actuator, and visa versa, by meansof pushrod 644 which holds the actuators in tension relative to oneanother. As a result, each planar actuator 634 has no out-of-planeforces applied to it when the corresponding linear actuator 632 ispassive. The output motion of inner members 638 a (also referred to asactuator output members) of both actuators 632 and 634 may be controlledto exhibit axial motion and/or planar motion, respectively, as indicatedby arrows 640 a, 640 b to provide a desired actuation cycle or sequence.The construct of top cartridge 630 b may be identical but oriented toface bottom cartridge 630 a such that the concave side of the cartridgefaces outward.

A linkage portion in the form of a pushrod 644 extends between the innerfacing output members 638 a of actuator cartridges 630 a, 630 b, passingthrough and slidable within axially-aligned apertures within each of thelens stages. Adjacent the apertures within movable stages 626 b and 626c and oppositely or diametrically positioned from each other are clutchor break mechanisms 646 a, 646 b which are selectively engageable withpushrod 644 to fix the axial position of a respective lens stage. Theclutch mechanisms 646 a, 646 b may have any suitable construct,including but not limited to a frictional bearing surface or a tooth forcooperative engagement with a corresponding groove on pushrod 644.

In operation, selective actuation of the linear and planar actuators632, 634 of the two actuator cartridges 630 a, 630 b enable the cyclicalmotion of pushrod 644 to incrementally translate lens stages 626 b, 626c. Such incremental or “inchworm” motion is schematically illustrated inFIGS. 24B-24F. FIG. 24B shows guide rail 644 in a neutral position,i.e., not engaged with either lens stage 626 b or 636 c, when bothactuators 632, 634 are inactive. To move lens stage 626 b in a forwarddirection, a first portion 636 a of EAP film of each planar actuator 634(i.e., top and bottom in FIGS. 23A and 23B) is activated, as shown inFIG. 24C, to move pushrod 644 laterally from the neutral position toengage clutch mechanism 646 a (not shown in this figure). Next, asillustrated in FIG. 24D, linear actuator 632 is activated while firstportion 636 a of each planar actuator 634 remains active to move theoutput members 638 a out of plane. This out of plane motion pushes orlifts pushrod 644 and, thus, lens stage 626 b in a forward direction.Once moved to the desire axial position, pushrod 644 is disengaged fromclutch 646 a by deactivating the first EAP portion 636 a of each planaractuator 634, as illustrated in FIG. 24E. Finally, each linear actuator632 is deactivated to retract pushrod 644 to its neutral position, asshown in FIG. 24F. To move lens stage 626 c, the process is repeated butwith activating the second EAP portion 636 b of planar actuator 634instead of the first EAP portion 636 a. Separately activatable phases,i.e., EAP film portions, may be added to each planar actuator 634 alongwith additional clutch mechanisms to enable the lens displacementmechanism to move both lens stages, or more stages as the case may be,in tandem.

FIGS. 25A-25C illustrate another lens displacement system 650 which hasboth focusing and zoom capabilities. System 650 includes two integratedsingle phase, spring biased actuators—one having a single frustumdiaphragm configuration 652 and the other a double frustum diaphragmconfiguration 654. Actuator 652 includes a lens barrel structure 656housing a focusing lens assembly 658. Proximal to lens assembly 658along the focal axis of the system is afocal lens assembly 660 housedwithin a barrel structure 662. The two lens barrels 656, 662 are biasedaway from each other by coil spring 664. Further integrating the twoactuators, is a radially extending lateral structure 666 to which theouter frame or output members 668 a, 668 b of actuators 652, 654,respectively are coupled. Stretched between outer frame 668 a and acorresponding inner frame or output member 672 mounted to the distal endof lens barrel 656 of focusing actuator 652 is EAP film 670. Then,stretched between outer frame 668 b and a corresponding inner frame oroutput member 674 mounted to the proximal end of lens barrel 662 is afirst EAP film 676 a. A second EAP film 676 b is stretched between innerframe 674 and a grounded outer frame or output member 668 c to form thedouble diaphragm structure of zoom actuator 654. A second coil spring678 biases the coupled outer frames 668 a, 668 b from grounded outerframe 668 c.

As illustrated in FIG. 25A, all phases of the system actuators arepassive with focus at the “infinity” position. Focusing the systeminvolves activating EAP film 670 of focus actuator 652, as illustratedin FIG. 25B. The preload placed on lens barrel 656 allows it to advancein the direction of arrow 680 to provide a reduced focal length. Theamount of displacement undergone by lens barrel 656 may be controlled bythe controlling the amount of voltage applied to actuator 652. Zoomactuation is similar but with the activation of actuator 654, asillustrated in FIG. 25C in which voltage is applied to both EAP films676 a, 676 b to advance lens barrel 662 in the direction of arrow 682.As with focusing, the extent of zoom displacement may be controlled byregulating the amount of voltage applied to actuator 654. To obtainmagnitudes of greater displacement, additional actuator stages in aseries arrangement may be employed. To provide incremental zoomdisplacement, actuator 654 may be operated in two phases whereby the twodiaphragms are activated independently of each other. While the figuresshow independent operation of the focus (FIG. 25B) and zoom (FIG. 25C)lens assemblies, both may be operated simultaneously or controlled intandem to provide the desired combination of focus and zoom for aparticular lens application.

FIGS. 26A and 26B show another displacement mechanism 690 suitable forlens image stabilization. The actuator mechanism has a multi-phased EAP696 stretched between an outer frame mount 692 and a central output discor member 694. The output disc 694 is mounted to a pivot 698 whichbiases the disc out-of-plane. At rest, as illustrated in FIG. 26A, allphases or portions of multi-phased film are passive and the output disc694 is horizontal. When a selected portion or portions (out of anynumber of separately activatable portions) of film 696 a is/areactivated, the biased film relaxes in the activated area 696 a causingasymmetry in the forces on the output platform 694 and causing it totilt, as shown in FIG. 26B. The various activatable portion can beselectively activated to provide three-dimensional displacement of animage sensor or mirror (not shown but otherwise positioned atop thecenter disc or output member 694) in response to system shake.

The displacement mechanism of FIGS. 26A and 26B can be further modifiedto compensate for undesirable z-direction movement undergone by an imagesensor. Such a displacement mechanism 700 is illustrated in FIGS.27A-27C, where instead of pivotally mounting the actuator's outputmember 704 to ground, a spring biasing mechanism 708 is employed. Alsousing a multi-phased film 706, when one 706 a, or less than all phasesare activated, as illustrated in Fig: 27B, the actuator output disc 704under goes asymmetric tilting and axial translation. Where all of thefilm portions 706 are activated simultaneously or where some arcactivated to provide a symmetrical response, output member 704 undergoesa purely linear displacement in the axial direction, as illustrated inFIG. 27C. The magnitude of this linear displacement may be controlled byregulating the voltage applied to all phases or selecting the relativenumber of film portions that are activated at the same time.

The present invention also provides shutter/aperture mechanisms for usewith imaging/optical systems, such as those disclosed herein, where itis necessary or desirable to close a lens aperture (shutter function)and/or to control the amount of light passing to an optical element orcomponent (aperture function). FIG. 28 illustrates one suchshutter/aperture system 710 of the present invention which employs anEAP actuator 712 to actuate a plurality of cooperating plates or blades724 to adjust the passage of light through imaging pathway. Actuator 712has a planar configuration having a two-phase EAP film 718 a, 718 bextending between outer and inner frame members 714, 716, where theinner frame member has an annular opening 715 for passing light. Whileonly two film portions 718 a, 718 b are employed in the illustratedembodiment, a multiphase film may also be used. The mechanical/movingcomponents of the shutter/aperture are housed within a cartridge 723having top and bottom plates 720 a, 720 b, each having respectiveopenings 725 a, 725 b for passing light therethrough.

Aperture blades 724 have curved or arched teardrop shapes whereby theirannular alignment is held in an overlapping planar arrangement. Theblades are pivotally mounted to bottom plate 720 by means of upwardlyextending cam pins 736 which correspondingly mate with respective holesextending through the broader ends of blades 724, thereby defining apivot or fulcrum point about which the blades operatively pivot. Thetapered ends of the blades point in the same direction, with theirconcave edge defining the lens aperture, the opening size of which isvariable by selective pivoting of blades 724. Blades 724 each have a camfollower slot 730 through which another set of cam pins 732 extend fromthe bottom side of a rotating collar 722 positioned on the opposing sideof blades 724 (as illustrated in FIG. 28A). Cam follower slots 730 arecurved to provide the desired arched travel path by cam pins 732 ascollar 722 is rotated, which in turn, pivots curved blades 724 abouttheir fulcrums. A pin 726 extending from the top or actuator-facing sideof collar 722 protrudes through opening 725 a of top cartridge plate 720a mates with a hole 717 within inner frame member 716 of actuator 712.Selective activation of the actuators two-phase film 718 causes inneractuator frame 716 to move laterally in-plane in opposing directions.The actuator's output motion, through the pulling/pushing of collar pin726, rotates collar 727 and, thus, cam pins 732 within cam slots 730within the respective aperture blades 724. This in turn pivots theblades, thereby moving the tapered ends of the blades closer together orfarther apart to provide a variable aperture opening, which is bestillustrated in top view of cartridge 723 in FIG. 29B. The size of theaperture opening may be varied between fully open (FIG. 29A) and fullyclosed (FIG. 29C) to operate as a lens shutter.

FIGS. 36A-36D illustrate another aperture/shutter mechanism 840 of thepresent invention. Mechanism 840 includes a planar base 842 on which anaperture/shutter blade 844 is pivotally mounted at one end to a pivotpoint 845. Pivotal movement of blade 844 moves its free end in a planeback and forth over light-passing image aperture 854. Movement of blade844 is accomplished by pivotal movement of a lever arm 846 having a freeend movably received within a notch 856 within the interior edge ofblade 844. Lever arm 846 is pivotally mounted to base 842 at a pivotpoint 852 a. A flexure 848 integrally coupled or formed as a monolithicpiece with lever arm 846 extends between first pivot point 852 a andsecond pivot point 852 b. A tab 850 extends from a central point onflexure 848 inward toward aperture 854. The blade, lever arm, andflexure may be adapted to provide aperture 854 in a normally open stateor normally closed state.

Movement of tab 850 toward aperture 854 in the direction of arrow 860 adeflects flexure 848 in the same direction, as illustrated in FIG. 36C.This action, in turn, rotationally pivots lever arm 846 in the directionof arrow 860 b, causing the free end of the lever arm to move withinnotch 856 toward pivot point 845, which in turn causes blade 844 topivotally rotate in the direction of arrow 860 c thereby coveringaperture 854. Such actuation is caused by activation of actuator 856which is mounted or stacked on top of the moving components of mechanism840, as illustrated in FIG. 36D. Actuator 856 comprises a two-phase EAPfilm 860 a, 860 b configuration, similar to that actuator 710 of FIG.28, extending between outer and inner frame members 858 a, 858 b,respectively. The free end of tab 850 is mechanically coupled to innerframe member 858 b. Based on the orientation of actuator 856 relative toshutter mechanism 840 illustrated in FIG. 36D, activation of EAP section860a alone pushes tab 850 outward, while activation of EAP section 860 balone pulls tab 850 inward.

As illustrated, mechanism 840 functions primarily as a shutter, withaperture 854 being either open or closed. Providing a hole 862 (shown inphantom in FIG. 36A) within blade 844 which aligns with aperture 854when blade 844 is in the closed position, and which has a diameter whichis smaller than that of aperture 854, enables the mechanism to functionas an aperture mechanism with two settings—one with the blade in an openposition, thereby letting more light pass through aperture 854 to a lensmodule, and another with the blade closed over aperture 854, therebypassing light through smaller hole 862.

Other lens displacement mechanisms may impart movement to a lens or lensstack by use of an actuator employing a “unimorph” film structure orcomposite. FIGS. 30A and 30B show a cross-section of a segment of such afilm structure 740. Film structure comprises an elastomeric dielectricfilm 742 bonded to a film backing or substrate 744 which is relativelystiffer, i.e., has a higher elastic modulus, than dielectric film 742.These layers are sandwiched between a flexible electrode 746 on theexposed side of dielectric film 742 and a stiffer electrode 748 eitheron the inner or exposed side of stiff film backing 744. As such, thecomposite structure 740 is “biased” to deflect in only one direction. Inparticular, when the film structure 740 is activated, as illustrated inFIG. 30B, dielectric film 742 is compressed and displaced laterally,causing the structure to bow or arch in a direction away from substrate744. The biasing imposed on the structure may be effected in any knownmanner, including those generally described in International PublicationNo. WO98/35529. Several lens displacement mechanisms of the presentinvention employing such a unimorph type EAP actuator are now described.

Lens displacement system 750 of FIGS. 31A and 31B includes a lens barrelor assembly 754 coupled to an actuator mechanism which utilizes aunimorph EAP film structure 752. A selected area or length of the filmstructure 752 extends between the lens barrel 754 and a fixed basemember 756. The film structure may be a monolithic piece which surroundsthe lens barrel like a skirt, which may comprise a single phasestructure or multiple addressable areas to provide multi-phase action.Alternatively, the actuator may comprise multiple discrete segments offilm which may be configured to be collectively or independentlyaddressable. In either variation, the stiffer film side or layer (i.e.,substrate side) faces inward such that the film is biased outward. Uponactivation of the film, as illustrated in FIG. 31 B, the film expands inthe biased direction causing the film to extend away from its fixedside, i.e., away from base member 756, thereby moving lens barrel 754 inthe direction of arrow 758. Various parameters of the film compositee.g., film area/length, variance elasticity between EAP layer andsubstrate layer, etc., may be adjusted to provide the desired amount ofdisplacement to affect auto focus and/or zoom operation of the lenssystem.

Lens displacement mechanism 760 of FIGS. 32A and 32B also employs aunimorph film actuator. System 760 includes a lens barrel or assembly762 mounted to lens carriage 764 which rides on guide rails 766.Actuator 770 comprises folded or stacked unimorph film sheets coupledtogether in series fashion. In the illustrated embodiment, each unimorphsheet is constructed with the more flexible side 772 a facing the lensbarrel and the stiffer side 772 b facing away from the lens barrel, butthe reverse orientation may be employed as well. When all of theactuator sheets are inactive, the stack is at its most compressed toposition, i.e., lens barrel 762 is in the most proximal position, asillustrated in FIG. 32A. In the context of a focusing lens assembly,this position provides the greatest focal length whereas, in the contextof an afocal lens assembly, the zoom lens is in the macro position.Activation of one or more sheets 772, either collectively orindependently, displaces lens barrel 762 in the direction of arrow 765to adjust the focus and/or magnification of the lens system.

Under certain environmental conditions, such as in high humidity andextreme temperature environments, the performance of an EAP actuator maybe affected. The present invention addresses such ambient conditionswith the incorporation of a feature which may be integrated into the EAPactuator itself or otherwise constructed within the system withoutincreasing the system's space requirements. In certain variations, theEAP actuators are configured with a heating element to generate heat asnecessary to maintain or control the humidity and/or temperature of theEAP actuator and/or the immediately surrounding ambient environment. Theheating element(s) are resistive, having a conductor either integratedinto or adjacent to the EAP film, where the voltage across the conductoris lower than that required for activation of the actuator. Employingthe same EAP actuator used for lens displacement and/or imagestabilization to control ambient parameters of the system furtherreduces the number of components in the system and its overall mass andweight.

FIG. 33A illustrates an exemplary EAP actuator 780 usable with thelens/optical systems of the present invention employing a serieselectrode arrangement for the heating function. The view shows theground side of the actuator with ground electrode pattern 782 and thehigh voltage electrode pattern 784 on the other side of actuator 780shown in phantom. Lugs 786 a and 786 b establish electrical connections,respectively, to the ground and high voltage inputs from the system'spower supply (not shown) for operating the actuator. A third lug orconnector 786 c provides connection to a low voltage input from thepower supply for the series resistive heater current path. Arrows 788show the annular current path provided by the electrode arrangementwhich uses the entire ground electrode 782 as a resistive heatingelement.

FIG. 33B illustrates another EAP actuator 790 which employs a parallelelectrode arrangement for the heating function. This view shows theground side of the actuator with ground electrode pattern 792 with thehigh voltage electrode pattern 794 shown in phantom from the other sideof actuator 790. Lugs 796 a and 796 b establish electrical connections,respectively, to the ground and high voltage inputs from the system'spower supply (not shown) for operating the actuator. Parallel bus bars798 a, 798 b are provided on the ground side of actuator 790 forconnection to the ground and low voltage inputs, respectively, from thepower supply (not shown). Arrows 800 illustrate the radial path of thecurrent established by the parallel electrode arrangement. Using theelectrode in a parallel as opposed to series fashion allows for the useof a lower voltage to achieve the current flow necessary to induceheating of the film.

As mentioned above, another approach to system humidity and temperaturecontrol is the use of a resistive heating element positioned adjacentthe EAP actuator.

FIG. 34 illustrates a lens displacement mechanism 810 employing EAPactuator having EAP film 812. The spacing 816 defined between the tophousing/cover 813 and EAP film 812 provides sufficient space in which toposition a heating element 814. Preferably, the heating element has aprofile and size that matches that of the EAP film—in this case, afrustum shape as illustrated in FIG. 34A, in order to minimize spacingrequirements of the system and to maximize heat transfer between theheating element 814 and EAP film 812. The heating element includes aresistive trace 815 a on an insulating substrate 815 b and electricalcontacts 818 to electrically couple the heating element to the system'spower and sensing electronics.

Another optional feature of the lens displacement systems of the presentinvention is the provision of a sensor to sense the position of a lensor lens assembly which provides closed loop control of the lensdisplacement. FIG. 35 illustrates an exemplary embodiment of such aposition sensing arrangement incorporated into the lens displacementsystems 820, having a similar construct to the lens displacement systemof FIG. 7A. The sensing arrangement comprises a nested electrode pairhaving cylindrical configurations. One electrode 822 a, e.g., the groundside electrode, encircles an exterior portion of lens barrel 824. Groundelectrode 822 a is electrically coupled to ground lead 830 a throughactuator biasing spring 830. The other electrode 822 b, e.g., the activeor power/sensing electrode 822 b, encircles the interior surface of abushing wall 826 extends upwards from the back end of housing 828 and isseated between actuator biasing spring 830 and the outer surface of lensbarrel 824. Electrode 822 b is electrically coupled to power/sensinglead 830 b. An insulating material adhered to the active electrode 822 bmay be provided in the gap defined between the two electrodes to providea capacitive structure. With the position of the lens barrel asillustrated, the capacitance across the electrodes is at its greatest.As lens barrel 824 is displaced in the distal direction, the overlappingsurface areas of the electrodes decreases, in turn reducing thecapacitive charge between them. This change in capacitance is fed backto the system's control electronics (not shown) for closed loop controlof the lens position.

By use of the EAP actuators for auto-focusing, zoom, image stabilizationand/or shutter control, the subject optical lens systems have minimizedspace and power requirements and, as such, are ideal for use in highlycompact optical systems such as cell phone cameras.

Methods of the present invention associated with the subject opticalsystems, devices, components and elements are contemplated. For example,such methods may include selectively focusing a lens on an image,selectively magnifying an image using a lens assembly, and/orselectively moving an image sensor to compensate for unwanted shakeundergone by a lens or lens assembly. The methods may comprise the actof providing a suitable device or system in which the subject inventionsare employed, which provision may be performed by the end user. In otherwords, the “providing” (e.g., a lens, actuator, etc.) merely requiresthe end user obtain, access, approach, position, set-up, activate,power-up or otherwise act to provide the requisite device in the subjectmethod. The subject methods may include each of the mechanicalactivities associated with use of the devices described as well aselectrical activity. As such, methodology implicit to the use of thedevices described forms part of the invention. Further, electricalhardware and/or software control and power supplies adapted to affectthe methods form part of the present invention.

Yet another aspect of the invention includes kits having any combinationof devices described herein—whether provided in packaged combination orassembled by a technician for operating use, instructions for use, etc.A kit may include any number of optical systems according to the presentinvention. A kit may include various other components for use with theoptical systems including mechanical or electrical connectors, powersupplies, etc. The subject kits may also include written instructionsfor use of the devices or their assembly. Such instructions may beprinted on a substrate, such as paper or plastic, etc. As such, theinstructions may be present in the kits as a package insert, in thelabeling of the container of the kit or components thereof (i.e.,associated with the packaging or sub-packaging) etc. In otherembodiments, the instructions are present as an electronic storage datafile present on a suitable computer readable storage medium, e.g.,CD-ROM, diskette, etc. In yet other embodiments, the actual instructionsare not present in the kit, but means for obtaining the instructionsfrom a remote source, e.g. via the Internet, are provided. An example ofthis embodiment is a kit that includes a web address where theinstructions can be viewed and/or from which the instructions can bedownloaded. As with the instructions, this means for obtaining theinstructions is recorded on suitable media.

As for other details of the present invention, materials and alternaterelated configurations may be employed as within the level of those withskill in the relevant art. The same may hold true with respect tomethod-based aspects of the invention in terms of additional acts ascommonly or logically employed. In addition, though the invention hasbeen described in reference to several examples, optionallyincorporating various features, the invention is not to be limited tothat which is described or indicated as contemplated with respect toeach variation of the invention. Various changes may be made to theinvention described and equivalents (whether recited herein or notincluded for the sake of some brevity) may be substituted withoutdeparting from the true spirit and scope of the invention. Any number ofthe individual parts or subassemblies shown may be integrated in theirdesign. Such changes or others may be undertaken or guided by theprinciples of design for assembly.

Also, it is contemplated that any optional feature of the inventivevariations described may be set forth and claimed independently, or incombination with any one or more of the features described herein.Reference to a singular item, includes the possibility that there areplural of the same items present. More specifically, as used herein andin the appended claims, the singular forms “a,” “an,” “said,” and “the”include plural referents unless the specifically stated otherwise. Inother words, use of the articles allow for “at least one” of the subjectitem in the description above as well as the claims below. It is furthernoted that the claims may be drafted to exclude any optional element. Assuch, this statement is intended to serve as antecedent basis for use ofsuch exclusive terminology as “solely,” “only” and the like inconnection with the recitation of claim elements, or use of a “negative”limitation. Without the use of such exclusive terminology, the term“comprising” in the claims shall allow for the inclusion of anyadditional element—irrespective of whether a given number of elementsare enumerated in the claim, or the addition of a feature could beregarded as transforming the nature of an element set forth in theclaims. Stated otherwise, unless specifically defined herein, alltechnical and scientific terms used herein are to be given as broad acommonly understood meaning as possible while maintaining claimvalidity.

In all, the breadth of the present invention is not to be limited by theexamples provided. That being said, we claim:

1. An optical system comprising: at least one lens; an image sensorpositioned to receive images from the at least one lens; and at leastone electroactive polymer actuator comprising an electroactive filmstretched within a frame and maintained in a non-planar concave orconvex configuration, where a portion of the electroactive film iscoupled to the image sensor for selectively stabilizing movementundergone by the image sensor.
 2. The optical system of claim 1, whereinthe at least one lens is a focusing lens.
 3. The optical system of claim1, wherein the at least one lens is a zoom lens.
 4. The optical systemof claim 1, wherein the actuator is configured for selectivelystabilizing movement relative to the image sensor in the x-y planerelative.
 5. The optical system of claim 1, wherein the actuator isconfigured for selectively stabilizing movement to the image sensor inthe z-direction relative.
 6. The optical system of claim 1, furthercomprising a bearing structure interposed between the image sensor andthe actuator to facilitate transmission of output motion from theactuator to the image sensor.
 7. The optical system of claim 6, whereinthe bearing structure comprises a planar substrate having a plurality ofshock absorbing elements.
 8. The optical system of claim 7, wherein thesubstrate comprises an electronic circuit providing electrical contactbetween the image sensor and control electronics.
 9. The optical systemof claim 1, wherein the electroactive film comprises a plurality ofindependently activatable portions.
 10. A method of stabilizing an imageprovided by an optical lens system, the method comprising: providing atleast one optic lens and an image sensor positioned for receiving animage from the lens; and maintaining an electroactive polymer film in astretched configuration to form a concave or convex shape within anelectroactive polymer actuator; selectively activating an electroactivepolymer actuator to deflect a portion of the electroactive film toadjust the position of the image sensor in response to motion undergoneby the image sensor.
 11. The method of claim 10, wherein selectivelyactivating the actuator comprises selectively activating a plurality ofelectroactive-portions of the actuator, wherein the portions areindependently activatable.
 12. The optical system of claim 1, where theelectroactive film is biased in the non planar configuration by adisplacement mechanism.
 13. The optical system of claim 12, where thedisplacement mechanism comprises a pivot.
 14. The optical system ofclaim 12, where the displacement mechanism comprises a spring mechanism.15. An optical system comprising: at least one lens; an image sensorpositioned to receive images from the at least one lens; and anelectroactive polymer actuator having an electroactive film capable ofasymmetrical displacement to provide for three-dimensional movement toselectively stabilize movement undergone by the image sensor.
 16. Theoptical system of claim 15, wherein the at least one lens is selectedfrom a group consisting of a focusing lens and a zoom lens.
 17. Theoptical system of claim 15, further comprising a hearing structureinterposed between the image sensor and the actuator to facilitatetransmission of output motion from the actuator to the image sensor. 18.The optical system of claim 17, wherein the bearing structure comprisesa planar substrate having a plurality of shock absorbing elements. 19.The optical system of claim 15, wherein the electroactive film comprisesa plurality of independently activatable portions.
 20. The opticalsystem of claim 15, where the electroactive film is biased in the nonplanar configuration by a displacement mechanism.